The invention concerns a bi-stable mechanism and its application to anti-theft device for motor vehicles.
There is considerable need for an extremely simple, economical and robust mechanical device capable of ensuring, in a simple and reliable manner, two stable positions. The purpose of the present invention is to provide such a device, particularly for the car lock industry.
According to the invention we provide a bi-stable mechanism comprising a housing, a lever pivotally mounted in said housing about an axis and movable between first and second stable positions, a spring for urging said lever towards one of said stable positions according to selection, said spring being a hairpin-type spring of which one end is connected to one end of the said lever and the other end mounted so as to pivot at a fixed point, the distance between the ends of the spring when the lever is in either stable position is greater than the distance between the point of location of the spring and the point of engagement of the spring end with the lever end when the lever is at its centre position whereby the spring becomes more compressed as the lever approaches the centre position where the lever is unstable.
The new bi-stable (toggle) mechanism to which the invention relates, which uses a hairpin spring, occupies very little space and at the same time provides considerable amplitude of movement, owing to the small distance between the two ends of the hairpin spring.